Inorganic/organic hybrid polymers have been known since about 1980. The principle structure of these materials is derived from the network structure of silica glass with Sixe2x80x94Oxe2x80x94Si bonds. Their synthesis takes place using the sol/gel process via the controlled hydrolysis and condensation of alkoxysilanes. If metal oxides are also included in the sol/gel process, then the silicate network can be modified in a controlled manner.
An organic network can also be assembled as a result of the polymerization of organo-functional groups which can be introduced into the material via organo-alkoxysilanes. Reactive methacrylate groups, epoxy groups or vinyl groups can be polymerized in this way by means of thermal or, as the case may be, photochemical induction.
DE 43 03 570 describes hybrid polymers which are designated ORMOCER(copyright) compounds.
Because of their possible breadth of structural variation, a series of different material properties can be set up and combined in inorganic/organic hybrid polymers (e.g. abrasion resistance, corrosion protection properties, barrier properties, etc.). Barrier properties of inorganic/organic hybrid polymers have been researched in regard to the permeation through them of oxygen, water vapor and hydrocarbons which derive from various types of different aroma-promoting substances translator: aromatic organic compounds?. It has been possible to detect a good to very good barrier property in all cases (see: Arnberg-Schwab, M. Hoffmann, H. Bader: xe2x80x9cKunststoffe 86xe2x80x9d, 1996, 5, pp. 660-664).
Approximately 3,000 organic compounds, to which a specific state of aggregation is assigned on the basis of their characteristic properties, form part of the group of liquid crystalline compounds. The phenomena of liquid crystalline compounds were observed in 1888 in cholesterol benzoate which actually melted at 145.5xc2x0 C. but which remained cloudy and turbid. The melt suddenly became clear only at 178.5xc2x0 C. On cooling, the effects occurred in the reverse sequential order (Mannschreck: xe2x80x9cChemiker-Zeitung 92xe2x80x9d, 1968, pp. 69-72).
Liquid crystalline compounds have been on the market since 1904 but the principles of their structure became recognized only much later. Thermotropic liquid crystalline compounds, which are obtained by heating crystals above their melting point, exhibit properties which lie between those of the liquid state and those of the solid state: they exhibit the mobility of liquids, which are generally isotropic, and also the optical anisotropy of crystals. Whereas in liquids, the molecules move freely in the three dimensions and are capable of rotating about three mutually vertically oriented axes and whereas in the solid state, by contrast, the molecules are fixed and are not able to rotate, in the liquid crystalline state, however, the molecules are capable of translation movements. The crystal lattice breaks down at the crystalline/liquid crystalline transition point but the molecules retain a preferred orientation: they become aligned parallel to one another. Liquid crystals lose their optical anisotropy property (turbidity as a consequence of the scattering of incident rays of light, double refraction and diffraction phenomena) only at the liquid crystalline/liquid transition point.
Liquid crystalline polymers (LCP) differ e.g. in regard to their crosslinking structures (backbones). Polymers with acrylate main chains, methacrylate main chains and siloxane main chains are the most common. A review regarding such compounds is given in Gray, G. W.: Synthesis and properties of side chain liquid crystal polysiloxanes, in xe2x80x9cSide Chain Liquid Crystal Polymersxe2x80x9d, 1992, pp. 106-129.
However, a disadvantageous feature of the liquid crystalline polymers (LCP) of the prior art is that although these do have improved barrier properties, especially with respect to oxygen, compared to non-liquid crystalline polysiloxanes, their barrier properties are not adequate for many applications. Thus the substrates, that are coated with these LCP, are still not satisfactory in regard to physical properties and, especially, in regard to scratch resistance.
Starting out from here, the problem for the present invention is therefore to propose new coating materials which exhibit good adhesion and excellent abrasion resistance and scratch resistance in addition to good barrier properties.
The problem is solved by the characterizing features of claim 1. The subsidiary claims show further advantageous forms of embodiments.